Shares in the temporary power company Aggreko plunged 22pc after it issued its
second profit warning in two months on the back of a gloomy outlook for 2013.

The FTSE 100, which powered the 2012 Games with its generators, said that now the Olympics contract had come to an end next year’s financial performance was likely to be worse than 2012.

It said the end of the contract, as well as declining military work as the US reduces the number of troops in Afghanistan and doubts over contract extensions in Japan, were likely to contribute to a £100m fall in revenues next year.

“After a year of strong growth in 2012, the economic environment we will be facing in 2013 is particularly uncertain in many of our markets and it is difficult at this stage to provide a definitive view of the likely pattern of trading in 2013,” the company said in a trading update for the full year.

“On a reported basis we currently believe that group performance in 2013 is likely to be slightly lower than in 2012,” it added.

It was the second profit warning from Aggreko in two months, and the company it was taking “a number of steps” to deal with the reality of the weakened outlook, including a reduction in investment next year.

Despite the warning on 2013 the company said revenue was likely to be around £1.6bn in the full year to December 31 2012, up 13pc, with profit before tax and amortisation up 12pc at £365m.

Aggreko said that while customers against whose accounts it has taken bad debt provisions - which partly drove a profit warning in October - had made “substantial” payments during the second half of the year, bad debt provisions were likely to be around $85m (£52m) by the end of the year.

John Lawson, analyst at Investec said the trading update contained “some very mixed messages” and was much more cautious than expected about the economic outlook for 2013.

He said however that while the update would be seen as “something of a setback ... we continue to believe that there are many structural drivers that should continue to drive earnings in the years to come.”

Investec lowered its recommendation on shares from “buy” to “hold”.

Aggreko said the fourth quarter had been stronger than the third in terms of orders, with major contracts in Cote d’Ivoire and Japan.

It is expecting to report a 24pc rise in revenues at its “Local” business for 2012, including its Olympics contract. Margins within the business are expected to rise two percentage points for the full year to 19pc.

“In the Local business, we expect to see continued underlying growth in 2013, and at this stage we believe that it will deliver another positive year,” the company said.

“In the market for International Power Projects, the weakening trend in economic growth in many emerging markets, which we identified in our October statement, has continued; our previous experience suggests that in these circumstances customers may in the short term be under less pressure to secure additional power generation.”

Aggreko said that while it expected both its Local and International Power Projects businesses to grow in 2013, it was unlikely to be enough to entirely offset the anticipated £100m fall in revenue and associated margin.